A301561 Sphenic Fibonacci numbers.

610, 987, 10946, 3524578, 9227465, 24157817, 39088169, 63245986, 1836311903, 7778742049, 20365011074, 591286729879, 4052739537881, 17167680177565, 44945570212853, 61305790721611591, 420196140727489673, 1500520536206896083277, 6356306993006846248183

Offset

1,1

Comments

Intersection of A000045 and A007304. There are 28 sphenic numbers among the first 200 positive Fibonacci numbers.

Links

Table of n, a(n) for n=1..19.

Formula

A000045 INTERSECT A007304.

Example

610 is a term since it is a Fibonacci number that is a product of 3 distinct primes, 610=2*5*61, which makes it a sphenic number.

Mathematica

Select[Fibonacci@Range[120], SquareFreeQ[#]&&PrimeNu[#]==3&]

Prog

(PARI) for(n=1, 120, fn=fibonacci(n); issquarefree(fn)&&omega(fn)==3&&print1(fn ", "))

Crossrefs

Cf. A000045, A007304, A061305 (squarefree Fibonaccis), A137563 (Fibonaccis with 3 distinct primes).

Sequence in context: A246881 A263393 A137563 * A204487 A090177 A120719

Adjacent sequences: A301558 A301559 A301560 * A301562 A301563 A301564

Keyword

nonn

Author

Waldemar Puszkarz, Mar 23 2018

Status

approved